/*--------------------------------------------------------------- 
 * Copyright (c) 1999,2000,2001,2002,2003                              
 * The Board of Trustees of the University of Illinois            
 * All Rights Reserved.                                           
 *--------------------------------------------------------------- 
 * Permission is hereby granted, free of charge, to any person    
 * obtaining a copy of this software (Iperf) and associated       
 * documentation files (the "Software"), to deal in the Software  
 * without restriction, including without limitation the          
 * rights to use, copy, modify, merge, publish, distribute,        
 * sublicense, and/or sell copies of the Software, and to permit     
 * persons to whom the Software is furnished to do
 * so, subject to the following conditions: 
 *
 *     
 * Redistributions of source code must retain the above 
 * copyright notice, this list of conditions and 
 * the following disclaimers. 
 *
 *     
 * Redistributions in binary form must reproduce the above 
 * copyright notice, this list of conditions and the following 
 * disclaimers in the documentation and/or other materials 
 * provided with the distribution. 
 * 
 *     
 * Neither the names of the University of Illinois, NCSA, 
 * nor the names of its contributors may be used to endorse 
 * or promote products derived from this Software without
 * specific prior written permission. 
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
 * NONINFRINGEMENT. IN NO EVENT SHALL THE CONTIBUTORS OR COPYRIGHT 
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 
 * ________________________________________________________________
 * National Laboratory for Applied Network Research 
 * National Center for Supercomputing Applications 
 * University of Illinois at Urbana-Champaign 
 * http://www.ncsa.uiuc.edu
 * ________________________________________________________________ 
 *
 * socket.c
 * by Mark Gates <mgates@nlanr.net>
 * -------------------------------------------------------------------
 * set/getsockopt and read/write wrappers
 * ------------------------------------------------------------------- */

#include "headers.h"
#include "util.h"

#ifdef __cplusplus
extern "C" {
#endif

/* -------------------------------------------------------------------
 * If inMSS > 0, set the TCP maximum segment size  for inSock.
 * Otherwise leave it as the system default.
 * ------------------------------------------------------------------- */

const char warn_mss_fail[] = "\
WARNING: attempt to set TCP maxmimum segment size to %d failed.\n\
Setting the MSS may not be implemented on this OS.\n";

const char warn_mss_notset[] = "WARNING: attempt to set TCP maximum segment size to %d, but got %d\n";

void setsock_tcp_mss(int inSock, int inMSS)
{
#ifdef TCP_MAXSEG
    int rc;
    int newMSS;
    Socklen_t len;

    assert(inSock != INVALID_SOCKET);

    if (inMSS > 0)
    {
        /* set */
        newMSS = inMSS;
        len = sizeof(newMSS);
        rc = setsockopt(inSock, IPPROTO_TCP, TCP_MAXSEG, (char *)&newMSS, len);
        if (rc == SOCKET_ERROR)
        {
            fprintf(stderr, warn_mss_fail, newMSS);
            return;
        }

        /* verify results */
        rc = getsockopt(inSock, IPPROTO_TCP, TCP_MAXSEG, (char *)&newMSS, &len);
        WARN_errno(rc == SOCKET_ERROR, "getsockopt TCP_MAXSEG");
        if (newMSS != inMSS)
        {
            fprintf(stderr, warn_mss_notset, inMSS, newMSS);
        }
    }
#endif
} /* end setsock_tcp_mss */

/* -------------------------------------------------------------------
 * returns the TCP maximum segment size
 * ------------------------------------------------------------------- */

int getsock_tcp_mss(int inSock)
{
    int theMSS = 0;

#ifdef TCP_MAXSEG
    int rc;
    Socklen_t len;
    assert(inSock >= 0);

    /* query for MSS */
    len = sizeof(theMSS);
    rc = getsockopt(inSock, IPPROTO_TCP, TCP_MAXSEG, (char *)&theMSS, &len);
    WARN_errno(rc == SOCKET_ERROR, "getsockopt TCP_MAXSEG");
#endif

    return theMSS;
} /* end getsock_tcp_mss */

/* -------------------------------------------------------------------
 * Attempts to reads n bytes from a socket.
 * Returns number actually read, or -1 on error.
 * If number read < inLen then we reached EOF.
 *
 * from Stevens, 1998, section 3.9
 * ------------------------------------------------------------------- */

ssize_t readn(int inSock, void *outBuf, size_t inLen)
{
    size_t nleft;
    ssize_t nread;
    char *ptr;

    assert(inSock >= 0);
    assert(outBuf != NULL);
    assert(inLen > 0);

    ptr = (char *)outBuf;
    nleft = inLen;

    while (nleft > 0)
    {
        nread = read(inSock, ptr, nleft);
        if (nread < 0)
        {
            if (errno == EINTR)
                nread = 0; /* interupted, call read again */
            else
                return -1; /* error */
        }
        else if (nread == 0)
            break; /* EOF */

        nleft -= nread;
        ptr += nread;
    }

    return (inLen - nleft);
} /* end readn */

/* -------------------------------------------------------------------
 * Attempts to write  n bytes to a socket.
 * returns number actually written, or -1 on error.
 * number written is always inLen if there is not an error.
 *
 * from Stevens, 1998, section 3.9
 * ------------------------------------------------------------------- */

ssize_t writen(int inSock, const void *inBuf, size_t inLen)
{
    size_t nleft;
    ssize_t nwritten;
    const char *ptr;

    assert(inSock >= 0);
    assert(inBuf != NULL);
    assert(inLen > 0);

    ptr = (char *)inBuf;
    nleft = inLen;

    while (nleft > 0)
    {
        nwritten = write(inSock, ptr, nleft);
        if (nwritten <= 0)
        {
            if (errno == EINTR)
                nwritten = 0; /* interupted, call write again */
            else
                return -1; /* error */
        }

        nleft -= nwritten;
        ptr += nwritten;
    }

    return inLen;
} /* end writen */

#ifdef __cplusplus
} /* end extern "C" */
#endif
